1. Field of the Invention
The present invention relates to a fastening bolt set which comprises an ordinary bolt, a special type of washer, an ordinary washer, and an ordinary nut, all them being connected by a string, for use in an object, the other side of which can not be reached by hand or by means of a tool, the working principle of the present invention being such that, in the case where the back side of a plate or other kind of object is unreachable, a hole big enough to receive a bolt and the special washer is made in the plate or the object, the bolt and the special washer connected by means of a string are inserted into the said hole, the string is pulled out until the bolt and the special washer are halted at the other side of the object, and then the bolt is fastened by means of an ordinary washer and an ordinary nut.
2. Description of the Prior Art
Korea Patent serial No. 86-6646 which was applied by the present applicant describes a similar device for securing the head of a bolt by means of a special type of washer.
In this prior art, a hole is made in the object to be fastened, and the head of a bolt is inserted into the hole. But in this case, a circular washer is divided into several pieces so as for them to be inserted into the said hole. The divided pieces of the circular washer are provided recesses so that, when the pieces are combined together, they should keep a constant thickness. The head of the bolt is inserted into the hole, and the divided pieces of the washer connected one another by means of a string which is also connected to the bolt are also inserted into the hole sequentially. If the string is pulled out, the divided pieces of the washer is combined forming a circular washer, and because this combined circular washer is larger than the hole, it keeps the head of the bolt from being taken out of the hole, thereby securing the bolt to the object to be fastened. Thus another object can be fastened to the said object. The above device is used in the case where the back side of an object is not reachable by hand or by means of a tool. Therefore the bolt and the divided pieces of the washer are inserted from the front through a hole. But when the string is pulled out, the divided pieces of the washer are not easily combined into a circular washer due to the numerousness of the pieces. Further, it is very troublesome to insert the plurality of the pieces of the circular washer into the hole, thereby consuming much time and making the work difficult and inefficient.
The device of this prior invention consists of two or more divided washer sections, through which a guide wire is connected. In this device, each section of the divided washer is passed through the fastening hole to the opposite side of the panel, and then, the two strands of the guide wire are pulled forward in order to make the divided washer sections get together at the head of the bolt. Therefore, this device can not perform the function of a nut, but only the original function of a washer. Further, the fastening strength of this washer is very weak, and therefore, it is liable to fall out from the head of a bolt. In order to prevent such phenomenon, an annular groove is formed on the head of the bolt, while an annular projection is formed on the washer. Further, in order to assure the sure assembling of the washer sections, a plurality of guide holes for the guide wire are required. Such complicated features of the said device pose as the main disadvantage because the manufacturing cost of the device is increased thereby.
As an another prior art, there is a device which comprises a plurality of anchors which are foldable/unfoldable like an umbrella. This device is inserted into a hole, and then, the anchors are made to be unfolded so that the bolt should be halted at the back side of the object. While this device is same in its use as the device of the present invention, its technical conception is quite different from that of the present invention, and therefore, comments on this device will not be made.